TWI520040B - Capacitive touch panel with improved environmental impact and its application - Google Patents

Description

Capacitive touch panel for improving environmental impact and its application

The present invention relates to a capacitive touch panel, and more particularly to a capacitive touch panel that improves environmental impact and its application.

The existing capacitive touch panel is a capacitor C formed by different electrodes as an inductor, and the formula of the capacitor is

Where A is the area where the two electrodes overlap each other, d is the distance between the two electrodes, and ε is the dielectric constant of the dielectric layer between the two electrodes. When a conductive object (such as a finger) is placed on the touch panel, it is like an additional electrode, which causes a change in the capacitance C. In order to measure the change of the capacitance C, the capacitor C is charged and discharged using a fixed current I for a certain time T to obtain a voltage V, by the relationship

It can be known that the voltage V changes with the capacitance C, so it can be judged by the change of the voltage V whether or not a conductive object is placed on the touch panel. If you substitute formula 1 into formula 2, you can get

Therefore, in addition to the amount of change in the conductive object on the capacitive touch panel, it also has an effect on the environmental change, because any factor that changes the current I, the dielectric coefficient ε, the area A, and the distance d will change the voltage. V, such as temperature, humidity, heavy pressure deformation, etc.

As shown in FIG. 1 , it is a schematic diagram of the capacitive touch panel being affected by pressure. The capacitive touch panel 10 has a sensing layer 12 and a shielding layer 14. When the operating surface of the capacitive touch panel 10 is deformed by pressure, the sensing area of the sensing layer 12 is reduced due to extrusion. It is known that the capacitance C becomes smaller when the area A is reduced, and therefore, the pressure will affect the sensing of the capacitive touch panel. Taking the change of the sensed value in FIG. 2 as an example, the sensed value is a sensed value of the representative capacitor C after the voltage V is converted via the ADC. The firmware performs calibration before sensing and sets environment-related parameters so that all sensed values are maintained between 20 and 40 when no conductors are in contact with the capacitive touch panel to eliminate environmental errors. Figure 2 is the top left image. When the contact exerts pressure on the capacitive touch panel, the sensing area becomes smaller due to the pressing, causing the sensing value to decrease, as shown in the upper right diagram of FIG. At this time, in order to make the sensing value in the range that can be normally represented, the firmware performs calibration, and the parameter is adjusted to return the sensing value to 20 to 40, as shown in the lower right figure of FIG. 2 . When the pressure is released, the sensing area A of the sensing layer 12 is returned to the original state, so that the capacitance C rises, but the parameter of the firmware is still set when the pressure is present, so that the ADC converts the sensing value and rebounds quickly, thus making There is a wrong judgment of the conductor contact, as shown in the lower left figure of Figure 2.

Therefore, a capacitive touch panel that improves the environmental impact is what it is.

It is an object of the present invention to provide a capacitive touch panel that improves environmental impact and its application.

According to the present invention, a capacitive touch panel for improving environmental impact includes a sensing layer for sensing an object contact, and an empty sensing line under the sensing layer, wherein the sensing layer is shielded when sensing the empty sensing line The influence of the object on the air induction line causes the sensed value of the air induction line to change only in response to environmental changes.

According to the present invention, an application method for improving an environmental impact capacitive touch panel includes a sensing layer for sensing object contact and an empty sensing line under the sensing layer, the application method including setting a basic a value, and then sensing the empty sensing line, wherein the sensing layer shields the object from the influence of the air sensing line, so that the sensing value of the empty sensing line changes only according to the environmental change, and the sensing value and the basis are The difference in value is compared to the threshold value, and when the difference is greater than the threshold value, the correction of the sensing layer is performed.

In order to improve the impact of the pressure environment, the present invention utilizes a dummy trace to sense changes in the environment. In order to make the empty sensing line unaffected by the finger, the empty sensing line is disposed under the sensing layer. When sensing the empty sensing line, the sensing layer forms a shielding structure, which separates the empty sensing line from the finger area above the sensing layer. The sensed value sensed by the air-sensing line will only change in response to environmental variability. Therefore, if the change of the sensed value is sensed according to the air-sensing line, it can be known whether the environment is changed or not, so that the firmware can correctly perform the correction of the sensing layer. In one embodiment, when the null sensing line is sensing, the voltage of the sensing layer is set to the grounding level to obtain a good shielding effect.

3 is an exploded perspective view of an embodiment of a capacitive touch panel of the present invention. The capacitive touch panel of the present embodiment is a four-layer board structure composed of an X-direction sensing layer 16, a Y-direction sensing layer 18, a shielding layer 20 and an element layer 22, and insulation between the two is separated from each other. The shielding layer 20 under the X-direction sensing layer 16 and the Y-direction sensing layer 18 can shield the influence of the element layer 22 on the X-direction sensing layer 16 or the Y-direction sensing layer 18 during operation. In this embodiment, the dummy sensing line 24 and the shielding layer 20 are disposed on the same layer, but the empty sensing line 24 and the shielding layer 20 are not electrically connected. In one embodiment, when the detection circuit is on the component layer 22, a hole is directly implanted in the insulator between the shield layer 20 and the component layer 22, causing the sensing circuit to sense the empty sense line 24 via the fill hole 26. In an embodiment, when the X-direction sensing layer 16 or the Y-direction sensing layer 18 is sensing, the empty sensing line 24 has the same voltage level as the shielding layer 20, and thus does not affect the shielding effect of the shielding layer 20.

In addition to hardware support, the firmware performs relevant processing procedures for the empty sensing line before or after the sensing layer is sensed to understand whether the environment changes or not, and needs to re-execute the correction to improve the environmental impact. 4 is a flow chart of an embodiment of a method for applying a capacitive touch panel of the present invention. Before the process starts, a base value (Base) is set, which is the average of the sensing values of the last few times of the empty sensing line, and represents the condition of the sensing environment. Next, in step S30, the sensed value is obtained by sensing the null sensing line, and in step S32, the difference between the sensed value and the base value is compared with a threshold value (Threshold), when there is a difference between the base value and the sensed value, Indicates that there may be environmental changes. When the difference between the sensed value and the base value is greater than the threshold value, it can be determined that the environment has a drastic change. At this step, step S34 is performed to perform correction of the sensing layer to adjust the capacitive touch panel to a stable state, and then in step S36. The sensed value is set as the base value. If it is less than the threshold value, step S38 is performed, the sensed value is averaged, and the base value is recalculated. In another embodiment, the user defines different threshold values for different environmental changes and performs different corrections.

The above description of the preferred embodiments of the present invention is intended to be illustrative, and is not intended to limit the scope of the invention to the disclosed embodiments. It is possible to make modifications or variations based on the above teachings or learning from the embodiments of the present invention. The embodiments are described and illustrated in the practical application of the present invention in various embodiments, and the technical idea of the present invention is intended to be equivalent to the scope of the following claims. Decide.

10. . . Capacitive touch panel

12. . . Sensing layer

14. . . Shield

16. . . X direction sensing layer

18. . . Y direction sensing layer

20. . . Shield

twenty two. . . Component layer

twenty four. . . Empty sensor

26. . . Filling hole

1 is a schematic diagram of a capacitive touch panel affected by pressure;

Figure 2 is a schematic diagram showing changes in the sensed value when subjected to pressure;

3 is an exploded perspective view of an embodiment of a capacitive touch panel of the present invention;

4 is a flow chart of an embodiment of a method for applying a capacitive touch panel of the present invention.

16. . . X direction sensing layer

18. . . Y direction sensing layer

20. . . Shield

twenty two. . . Component layer

twenty four. . . Empty sensor

26. . . Filling hole

Claims (9)

A capacitive touch panel for improving environmental impact, comprising: a sensing layer for sensing an object contact; an empty sensing line located below the sensing layer; and a shielding layer on the same layer as the empty sensing line, wherein the sensing When the layer is sensed, the shielding layer has the same voltage level as the empty sensing line; wherein, when the empty sensing line senses, the sensing layer shields the object from affecting the empty sensing line, so that the empty sensing line The sensed value changes only in response to environmental changes. The capacitive touch panel of claim 1, further comprising an element layer below the shielding layer. The capacitive touch panel of claim 1, wherein the shielding layer and the empty sensing line are not electrically connected to each other. A capacitive touch panel for improving environmental impact, comprising: a sensing layer for sensing an object contact; an empty sensing line located below the sensing layer; and a shielding layer located below the empty sensing line; wherein, the sensing When the line senses, the sensing layer shields the object from the influence of the empty sensing line, so that the sensing value of the empty sensing line changes only according to the environmental change. The capacitive touch panel of claim 4, further comprising an element layer below the shielding layer. An application method for improving environmental impact of a capacitive touch panel, the capacitive touch panel comprising a sensing layer for sensing object contact and an empty sensing line under the sensing layer, and comprising the same layer as the empty sensing line The shielding layer, the application method includes: Setting a basic value; sensing the empty sensing line, wherein the sensing layer shields the object from the influence of the air sensing line, so that the sensing value of the empty sensing line changes only according to the environmental change; the sensing value is The difference in the base value is compared with the threshold value; when the difference is greater than the threshold value, the correction of the sensing layer is performed; and when the sensing layer is sensed, the shielding layer has the same voltage level as the empty sensing line. The application method of claim 6, wherein the step of setting a base value comprises setting an average value of the sensed values to the base value. The application method of claim 6, wherein the step of performing the correction of the sensing layer comprises setting the base value to the sensing value when the difference is greater than a threshold value. The application method of claim 6 further includes setting the threshold according to different environmental changes.